Is std::promise broken on my machine (using g++-mp)?

Question

Is this code valid, or is my compiler broken?

#include <future>
#include <iostream>

int main() {
   std::cout << "doing the test" << std::endl;
   std::promise<bool> mypromise;
   std::future<bool> myfuture = mypromise.get_future();
   mypromise.set_value(true);
   bool result = myfuture.get();
   std::cout << "success, result is " << result << std::endl;
   return 0;
}

Here's the output:

$ g++-mp-4.8 -std=c++11 test.cpp
$ ./a.out
doing the test
Segmentation fault: 11
$ 

I'm using g++-mp-4.8, which is the gcc 4.8 from macports.

Am I going insane?

Answer 1

The dynamic linker may be linking your program to an old version of libstdc++, the one in /opt/local/lib/libstdc++.6.dylib

Since you're compiling with GCC 4.8 you need to use the new libstdc++ that comes with GCC 4.8, which is probably /opt/local/lib/gcc48/libstdc++.6.dylib

You should check whether /opt/local/lib/libstdc++.6.dylib is the library that comes with GCC 4.8 and use the right one if it isn't.

You can control that in various ways, the simplest (but not necessarily the best) would be to run:

export DYLD_LIBRARY_PATH=/opt/local/lib/gcc48/
./a.out

See http://gcc.gnu.org/onlinedocs/libstdc++/faq.html#faq.how_to_set_paths and http://gcc.gnu.org/onlinedocs/libstdc++/manual/using_dynamic_or_shared.html#manual.intro.using.linkage.dynamic for other info (which is not specific to Mac OS X)

Answer 2

Your code compiles and runs fine for me in Xcode. The output is

doing the test success, result is 1

The compiler is Apple LLVM 4.2

Thus, I suggest you have a compiler configuration problem